Sound cut short in viscous liquid (3)
I believe the answer is:
goo
'liquid' is the definition.
The definition and answer can be both substances as well as being singular nouns.
Perhaps you can see an association between them that I can't see?
'sound cut short in viscous' is the wordplay.
'sound' becomes 'go' (synonyms).
'cut short' means to remove the last letter.
'in viscous' becomes 'oo' (I can't justify this - if you can you should give a lot more credence to this answer).
'go' with its final letter removed is 'g'.
'g'+'oo'='GOO'
Can you help me to learn more?
(Other definitions for goo that I've seen before include "Sticky stuff or sickly sentiment" , "Sticky and slimy stuff" , "Sticky gunge" , "Anything sticky" , "Sticky substance (colloq.)" .)